The eight-time All-Star sat out the opening two games of the season, but the Lakers won both.
Bryant scored his first basket of the season on a layup off a pass from Luke Walton to give the Lakers a 7-0 lead 1:19 into the game against the Sonics.
He finished with 23 points as Los Angeles beat the Sonics 118-112, improving to 3-0.
In the locker room before the game, Bryant had said, "I'm ready to go. There's no swelling, no discomfort. I've had three really good days."
Bryant, 28, underwent arthroscopic surgery on his right knee in mid-July and did not play during the Lakers' exhibition season.
He led the NBA in scoring last season with a 35.4 average.
Asked if he thought he was back to stay, Bryant said, "I should be good. I didn't want to come back and be day-to-day."
Since he hasn't played for a long time, he expects his transition back into the game to be a work in progress.
Coach Phil Jackson said he planned to use Bryant in a "rotation, like in the early season" in his first game back.
"I'll definitely check with him as the game goes on," Jackson said.
Bryant was happy to see the Lakers play well in their opening two games, saying, "It feels great. I am just going to go out there and pick my spots. Our confidence is high."